A systematic enumeration of the genus Salix of Japan is provided. Chosenia and Toisusu are included in Salix. About 40 species have been recognized as distinct in recent floras of Japan, but they were reduced to 31 species in this work. Of these, 28 are recognized as native to Japan and three are supposedly imported from China or Korea. These are classified into four subgenera and 17 sections. Subgenus Urbanianae (Seemen) H.Ohashi is newly proposed. Thirty-seven natural hybrids are recognized. Four subspecies, one variety, ten forms and one nothosubspecies are newly proposed. They are indicated in a systematic list in this paper. Each taxon is enumerated with its original reference, selected bibliography and principal synonyms. Types of specific and infraspecific names are quoted after the original reference. Areas of distribution are shown for species and infraspecific taxa.

The vegetative morphology and asexual reproduction of the unicellular green alga Vitreochlamys aulata (Pascher) Batko (= Sphaerellopsis aulata (Pascher) Gerloff) collected in Kanagawa Prefecture were observed in detail under controlled laboratory conditions. Although the vegetative morphology of the Japanese V. aulata material agreed with that described by Pascher (1927), Ettl (1963), and Batko (1970), the mode of flagellar formation in newly formed daughter cells differed from that observed by Batko (1970). This is the first report on V. aulata from Japan.

Distribution of 31 popular plants (Tab. 1, Figs. 2 to 17) in Fukushima Prefecture, northern Japan was surveyed in cooperation with local botanists. Mallotus japonicus is restricted to the easternmost part of the prefecture. Justicia procumbens is restricted to the southern- and the northernmost part of the prefecture disjunctly. New habitat connecting them is expected on the Pacific side. Reynoutria sachalinensis advanced eastward scatteredly from its western domain. Main area of Indigofera pseudotinctoria, Lonicera japonica, Paederia scandens, and Cayratia japonica are in eastern half of the prefecture. Kerria japonica is not recorded from southwest corner of the prefecturre.